LIQUID LUNCH: Hardhats, one in an ironworkers-union T-shirt, belly up to Eamonn's bar during their lunch hour. Photo: Angel Chevrestt

HAMMERED AND NAILED: Two construction workers lounge at Eamonn’s Irish Bar & Restaurant — where they each downed five bottles of beer — then return to the nearby World Trade Center construction site and breeze past a “Safety First” poster at an entrance gate. (J.C. Rice)

(ANGEL CHEVRESTT)

Ground Zero hardhats are hitting the hard stuff at lunch — guzzling beers and shots at nearby bars before stumbling back to their dangerous jobs on the hallowed site, The Post has learned.

With cost overruns crossing the $2 billion mark and the 10th anniversary of 9/11 approaching, some reckless workers were seen on midday breaks last week filling their bellies with enough booze to become legally drunk.

The men then stumbled back to the site, where workers have reached the 78th floor of 1 World Trade Center as they attempt to build a virtually indestructible skyscraper.

Construction is now in a delicate phase that demands clear-headed concentration, with crews ascending to the upper floors of the 1,776-foot Tower 1 and 947-foot Tower 4 as part of a furious, round-the-clock schedule to complete four buildings, a transit hub and a memorial.

The Post spotted two dozen workers stream north from the site each day at about 11:45 a.m. and pack two Murray Street watering holes for their hourlong lunch breaks — the same pub pilgrimage hardhats were making two years ago from Ground Zero.

Once again, many skipped food entirely in favor of liquid refreshments — including bottles of beer, shots of whiskey and — in the case of one wasted worker — a pint glass nearly full of vodka.

That man, in a T-shirt, jeans and construction boots, was among two groups crammed into Eamonn’s Irish Bar & Restaurant at 41 Murray St. about noon on Wednesday.

A backslapping barkeep put ice into a pint glass for him, filled it three-quarters with Absolut vodka and topped the drink with a splash of soda.

Within about 30 minutes, the worker had drained the glass.

A second hardhat sitting next to him ordered two shots of Jim Beam bourbon and drank them in succession within about 15 minutes.

Their other buddies — a total of 12 workers — were busy soaking up the suds.

A beefy man in his 40s wearing an orange T-shirt and griping about grueling work on a “big rig” guzzled five Bud Light bottles. His pal, a younger, taller man in a yellow T-shirt, sucked down the same amount.

After about 45 minutes, the younger drinker seemed to fade, leaning his head on his hand.

Their presence didn’t surprise the bartender, who greeted them by name in his Irish brogue and refreshed their beers continuously.

“How’s the lunch crowd been this week?” asked one worker as he swigged from his longneck.

“Was busy Monday,” the bartender replied.

A group of seven left and headed back to the site at about 12:45 p.m.

The two in T-shirts left about 10 minutes later, walked east on Murray before entering the northeast entrance gate near Tower 2 just before 1 p.m.

They passed through a security gate adorned with a sign that read “Safety First” and, “Our #1 priority is to send our workers home safe to their families!” Once inside, they walked south to Tower 4, a 72-story high-rise at 150 Greenwich St. that’s about half finished.

On Thursday, a different crowd of about 12 jammed the bar at dimly lit Uncle Mike’s at 57 Murray St.

Workers started filing in at about 11:45 a.m., throwing down their hardhats on the bar, loosening their yellow reflective jackets and ordering rounds of beer — Budweisers, Heinekens and Coronas.

They lined the entire bar, ogling two barely dressed bartenders and swapping jokes about their construction work.

“I got hit by a two-by-four the other day, bro. It went boom,” said one Heineken drinker with a large bandage on the back of his bald head. “I got a concussion, bro. They wanted me to go to a hospital.”

The bartenders — Jessica, in a bikini with partially unzipped shorts, and Natalia, in a halter top and daisy dukes — worked the customers deftly, asking which unions they belonged to.

“Local 46,” one said proudly, referring to the metal-workers union.

Experts say four to five drinks in an hour is enough for a 200-pound man to blow a .10 — more than the state’s legal limit of .08 — on a Breathalyzer even with a full meal in his stomach.

None of the workers at Uncle Mike’s ordered food.

Jessica warned a worker in a stonecutters-union shirt to be careful, saying undercover reporters had been in the bar a few years ago and exposed hardhat drinking.

He snickered.

Indeed, this isn’t the first time The Post has reported on the problem.

In 2009, a crowd of World Trade Center workers were caught making a beeline to gin mills along Murray Street to throw back beers and shots — and boasting about their reckless behavior.

“We don’t have to worry until someone severs a hand,” joked one drinking worker at Biddy Early’s Pub & Restaurant at 43 Murray St.

The Port Authority, which oversees the site’s 3,000 construction workers, responded to that story by firing the hardhats it could identify and cracking down with more sweeps, which it said it did on a weekly basis to catch on-the-job imbibers.

Told that the situation has not changed two years later, a PA insider groaned.

“This is the last thing we need,” he said. “We can’t have monitors for all those workers.”

Ron Marsico, a PA spokesman, said the agency has continued to investigate lunchtime boozing — but couldn’t say how many workers have been fired.

“There have been checks,” he said. “We do have a zero-tolerance policy. If we determine a worker is intoxicated on the job, we will move to terminate him, and we’ve done so in the past.”

Eamonn’s and Uncle Mike’s both denied that Ground Zero workers drank before returning to work, saying they come in only after their shifts or order just food and water.

As for those who drink at lunchtime, “it’s mostly just financial workers, like guys who work for Goldman Sachs,” claimed a bartender at Eamonn’s who identified herself only as Rachel.

There have been a handful of accidents at the WTC site in the last two years, including a construction worker plunging two stories last March at Tower 1.